Volatile Acidity Of Wines Research Articles

Characterization of Indigenous Non-Saccharomyces Yeast Strains with Potential Use in Winemaking.

The vineyard is a great reservoir of autochthonous yeast strains whose composition is defined by different regional (edaphology, orography or climatology) and anthropological factors (cultivation systems or cultural practices). Most of this yeast diversity corresponds to non-Saccharomyces strains, some of which have potential use in winemaking. The oenological potential of 29 different native non-Saccharomyces strains belonging to 4 species (Lachancea thermotolerans, Torulaspora delbrueckii, Starmerella bacillaris and Metschnikowia spp.) was evaluated, using the autochthonous Saccharomyces cerevisiae XG3 strain as a control. Microfermentations with pure culture of each strain were performed in duplicate and the basic parameters and major volatiles of wines were analysed following official methodology. The best strain within each species was selected using a quantification matrix including the relevant oenological characteristics. The fermentative ability of non-Saccharomyces was lower than S. cerevisiae in all cases, but with differences among species. L. thermotolerans and T. delbrueckii showed higher fermentation rates than Starm. bacillaris, whereas Metschnikowia spp. presented a low fermentative power. At chemical level all non-Saccharomyces strains reduced the alcoholic content, the higher alcohols and the volatile acidity of wines and increased the content of glycerol, with differences among strains within a given species. T. delbrueckii and L. thermotolerans increased the total acidity of wines. The latter and Metschnikowia spp. strains produced lactic acid, which decreased the wine pH in the case of L. thermotolerans. According to their oenological traits the best rated strains of each species were Lt93, Td315, Mf278 and Sb474. In addition, the data obtained in pure fermentations were correlated to those chemical and aromatic compounds obtained with these non-Saccharomyces strains in sequential fermentations. Autochthonous strains of non-Saccharomyces yeast species contribute distinctive chemical characteristics to the wines. The correlations observed between wines fermented with the different non-Saccharomyces indigenous strains in pure and sequential fermentations suggest that their contribution to wine properties remains stable regardless of must composition or winemaking techniques.

Novel Integrated Flow-Based Steam Distillation and Titration System for Determination of Volatile Acidity in Wines.

Novel integrated flow-based steam distillation and titration system with spectrophotometric detection was developed for determination of volatile acidity in wines. Using the system, the distillation procedure was carried out in an automatic manner, starting with introducing into a heated steam distillation module a sample and subjecting it to steam distillation. Under selected conditions, all the analyte was transferred to the distillate; therefore, the system did not require calibration. The collected distillate and titrant were introduced into the next monosegments in varying proportions, in accordance with the developed titration procedure, and directed to the detection system to record the titration curve. The titration was stopped after reaching the end point of titration. Procedures for distillation and titration were developed and verified separately by distillation of acetic acid, acetic acid in the presence of tartaric acid as well as acetic acid, tartaric acid, and titratable acidity, with precision (relative standard deviation) and accuracy (relative error) for both procedures lower than 6.9 and 5.6%, respectively. The developed steam distillation and titration systems were used to determine volatile acidity in samples of white and rosé wines separately and as the integrated steam distillation and titration system, both with precision lower than 9.4% and accuracy better than 6.7%.

Selection and oenological comparison of Taiwan Black Queen grape wine yeasts

More than hundreds of private wineries have been established since the Taiwan Tobacco and Alcohol Administration Act was enacted on April 19, 2000. It is then essential to screen local wine yeast in order to develop quality wine with unique flavor. Black Queen grape is a main ingredient for red wine brewing in Taiwan. In this study, ethanol productivity of yeasts isolated from spontaneous fermentation of Black Queen grape must (17 and 30 °Brix) was determined. Seven yeasts identified as Saccharomyces cerevisiae by Biolog System with higher ethanol productivity were individually inoculated into Black Queen grape must to undergo fermentation at 25°C for 14 days. The ethanol contents and volatile acidity in wine were above 15% (v/v) and below 0.7 g/L, respectively. Compared to commercial wine yeasts A, B and C, HP01 fermented red wine contained the highest total ester content, color intensity, taste grade, and overall preference value. On the other hand, HS13 fermented red wine contained the highest ethanol, higher alcohols, fatty acids and phenolic compounds content. The mtDNA restriction fragments profiles of these two wine yeast strains were different from those of other yeast strains. Due to their superiority in oenological characteristics, HP01 and HS13 can be applied in Black Queen red wine brewing to produce red wine with unique flavor.

Influence Of Yeast And Lactic Acid Bacteria On The Content Of Volatile Compounds And Other Oenological Parameters Of Wines

Abstract The effect of Saccharomyces cerevisiae yeast on the content of volatile compounds, ethanol, glycerol and volatile acidity of wines as well as the importance of inoculation with non-Saccharomyces and S. cerevisiae yeast for improving the aromatic complexity and characteristic features of wines were discussed in the paper. Moreover, the consequence of sequential inoculation of S. cerevisiae and lactic acid bacteria Oenococcus oeni on the content of volatile compounds, diacetyl, acetoine, volatile acidity, degradation of malic acid, content of diethyl succinate, ethyl lactate, biogenic amines was presented. The advantage of simultaneous inoculation, which is the reduction of fermentation time, was emphasized. The work highlights the role of indigenous strains of yeast and lactic acid bacteria in increasing the regional character of wines. The importance of enzymes produced by yeast and bacteria, as well as the increased interest in the ability of non-O. oeni species, such as Lactobacillus and Pediococcus, to perform malolactic fermentation were also discussed. 1. Introduction. 2. Alcoholic and malolactic fermentation. 3. Effect of yeast and lactic acid bacteria on oenological parameters of wines. 3.1. S. cerevisiae. 3.2. Non-Saccharomyces. 3.3. Lactic acid bacteria. 4. Summary

Effect of ethanol adaption on the inactivation of Acetobacter sp. by pulsed electric fields

The effects of low concentrations of ethanol (3% to 9%, v/v) on cell membrane fatty acid composition, membrane lipid conformation, membrane fluidity and pulsed electric fields (PEF) resistance of Acetobacter sp. in the stationary phase were investigated. Results showed that the growth of Acetobacter sp. was inhibited, and analysis of gas chromatography–mass spectrometry, Raman spectroscopy and fluorescence polarization indicated that membrane fluidity of Acetobacter sp. cells was significantly increased by modifying membrane fatty acid composition and membrane lipid conformation after exposure to ethanol. Moreover, results showed that cells cultivated in the medium with relatively high ethanol concentrations were more vulnerable to PEF. For example, the inactivation of Acetobacter sp. (109 CFU/mL) cultivated with 9% ethanol by PEF (20.0 kV/cm, 6.0 ms) could reach 5.17 log, significantly higher than those cultivated without ethanol (3.22 log). This was confirmed by morphological analysis, showing various changes on the cell surface after PEF treatment. Acetobacter sp. is one of spoilage microorganisms in winemaking, and it is able to convert the ethanol produced by yeasts into acetic acid and thereby increase volatile acidity in wine. In this study, the effect of ethanol as a growth substrate on PEF resistance in Acetobacter sp. cells was investigated. Results here reported will contribute to better understand the influencing mechanisms of ethanol on the inactivation of Acetobacter sp. cells by PEF treatment and further develop the application of PEF for inactivating acetic acid bacteria (AAB) in the wine industry.

Biological Demalication and Deacetification of Musts and Wines: Can Wine Yeasts Make the Wine Taste Better?

Grape musts sometimes reveal excess acidity. An excessive amount of organic acids negatively affect wine yeasts and yeast fermentation, and the obtained wines are characterized by an inappropriate balance between sweetness, acidity or sourness, and flavor/aroma components. An appropriate acidity, pleasant to the palate is more difficult to achieve in wines that have high acidity due to an excess of malic acid, because the Saccharomyces species in general, cannot effectively degrade malic acid during alcoholic fermentation. One approach to solving this problem is biological deacidification by lactic acid bacteria or non-Saccharomyces yeasts, like Schizosaccharomyces pombe that show the ability to degrade L-malic acid. Excessive volatile acidity in wine is also a problem in the wine industry. The use of free or immobilized Saccharomyces cells has been studied to solve both these problems since these yeasts are wine yeasts that show a good balance between taste/flavor and aromatic compounds during alcoholic fermentation. The aim of this review is to give some insights into the use of Saccharomyces cerevisiae strains to perform biological demalication (malic acid degradation) and deacetification (reduction of volatile acidity) of wine in an attempt to better understand their biochemistry and enological features.

Metschnikowia pulcherrima Influences the Expression of Genes Involved in PDH Bypass and Glyceropyruvic Fermentation in Saccharomyces cerevisiae.

Previous studies reported that the use of Metschnikowia pulcherrima in sequential culture fermentation with Saccharomyces cerevisiae mainly induced a reduction of volatile acidity in wine. The impact of the presence of this yeast on the metabolic pathway involved in pyruvate dehydrogenase (PDH) bypass and glycerol production in S. cerevisiae has never been investigated. In this work, we compared acetic acid and glycerol production kinetics between pure S. cerevisiae culture and its sequential culture with M. pulcherrima during alcoholic fermentation. In parallel, the expression levels of the principal genes involved in PDH bypass and glyceropyruvic fermentation in S. cerevisiae were investigated. A sequential culture of M. pulcherrima/S. cerevisiae at an inoculation ratio of 10:1 produced 40% less acetic acid than pure S. cerevisiae culture and led to the enhancement of glycerol content (12% higher). High expression levels of pyruvate decarboxylase PDC1 and PDC5, acetaldehyde dehydrogenase ALD6, alcohol dehydrogenase ADH1 and glycerol-3-phosphate dehydrogenase PDC1 genes during the first 3 days of fermentation in sequential culture conditions are highlighted. Despite the complexity of correlating gene expression levels to acetic acid formation kinetics, we demonstrate that the acetic acid production pathway is altered by sequential culture conditions. Moreover, we show for the first time that the entire acetic acid and glycerol metabolic pathway can be modulated in S. cerevisiae by the presence of M. pulcherrima at the beginning of fermentation.

The impact of cluster thinning on fertility and berry and wine composition of 'Blauer Portugieser' (<i>Vitis vinifera L.</i>) grapevine variety

<p><strong>Aim</strong>: Two different yield reductions based on cluster thinning (CT) were performed to determine their impact on vine growth, yield, and grape and wine composition of 'Blauer Portugieser' grapevine variety.</p><p><strong>Methods and results</strong>: Two levels of cluster thinning (limited CT1 – 20-30 % and severe CT2 – 40-50 % cluster reduction) were applied at the pea-size berry (BBCH 75) phenological stage in 2007, 2008 and 2011. The potential impact of CT was determined by measurements of vine growth and fertility potential, berry weight, berry colour, soluble solids content, titratable acidity, pH and total phenolics. Additionally, for the first time, individual phenolic compounds were identified and quantified in berry skin and wine by HPLC-MS. In general, CT of 'Blauer Portugieser' significantly decreased titratable acidity in grape and wine, and increased pH and chromatic parameters in grape and alcohol content and volatile acidity in wine. A significant decrease in yield per vine (of 0.92 kg of grape/vine), together with an increase in soluble solids (of 2.8 °Brix) in grape and pH and total extract content in wine was only observed in severe CT (CT2). Furthermore, CT2 significantly increased the content of total anthocyanins, flavonols and hydroxycinnamic acids, but not total flavanols, in grape and wine. CT2 significantly increased the content and proportion of <em>p</em>-coumaroyl pentose in grape and wine, catechin in grape, epicatechin in wine, quercetin-3-glucuronide (the main flavonol in 'Blauer Portugieser') in grape and wine, the content of myricetin-3-glucoside in grape, and the content of 3-glucosides of laricitrin, myricetin and quercetin in wine. Finally, CT2 increased the content and the proportion of 3-glucosides of delphinidin, petunidin and peonidin but decreased the proportion of malvidin-3-glucoside in grape and wine.</p><p><strong>Conclusion</strong>: A significant impact on yield and grape and wine composition was observed, particularly in the CT2 treatment, in which the yield loss was compensated by higher contents of soluble solids in grape, alcohol in wine, and phenolic compounds in grape and wine.</p><p><strong>Significance and impact of the study</strong>: The present study is the first report on the impact of different levels of cluster thinning on yield and grape and wine composition of 'Blauer Portugieser' variety. Grape and wine composition has been evaluated with an emphasis on a detailed profile of individual and total phenolic contents. The results are undoubtedly useful for winegrowers, who, until now, lacked technological guidelines to optimize 'Blauer Portugieser' yield and wine quality.</p>

Reduction of volatile acidity of acidic wines by immobilized Saccharomyces cerevisiae cells

Excessive volatile acidity in wines is a major problem and is still prevalent because available solutions are nevertheless unsatisfactory, namely, blending the filter-sterilized acidic wine with other wines of lower volatile acidity or using reverse osmosis. We have previously explored the use of an empirical biological deacidification procedure to lower the acetic acid content of wines. This winemaker's enological practice, which consists in refermentation associated with acetic acid consumption by yeasts, is performed by mixing the acidic wine with freshly crushed grapes, musts, or marc from a finished wine fermentation. We have shown that the commercial strain Saccharomyces cerevisiae S26 is able to decrease the volatile acidity of acidic wines with a volatile acidity higher than 1.44 g L(-1) acetic acid, with no detrimental impact on wine aroma. In this study, we aimed to optimize the immobilization of S26 cells in alginate beads for the bioreduction of volatile acidity of acidic wines. We found that S26 cells immobilized in double-layer alginate-chitosan beads could reduce the volatile acidity of an acidic wine (1.1 g L(-1) acetic acid, 12.5 % (v/v) ethanol, pH 3.12) by 28 and 62 % within 72 and 168 h, respectively, associated with a slight decrease in ethanol concentration (0.7 %). Similar volatile acidity removal efficiencies were obtained in medium with high glucose concentration (20 % w/v), indicating that this process may also be useful in the deacidification of grape musts. We, therefore, show that immobilized S. cerevisiae S26 cells in double-layer beads are an efficient alternative to improve the quality of wines with excessive volatile acidity.

Effect ofColletotrichum acutatumripe rot on the composition and sensory attributes of Cabernet Sauvignon grapes and wine

Background and Aim: The impacts of the fungal bunch rot pathogen Colletotrichum acutatum (ripe rot) on grape growing are documented; however, little is known about how the disease affects the resulting wine. This work aimed to investigate how ripe rot affects wine composition and sensory properties. Methods and Results: Wine was made using Cabernet Sauvignon grapes grown in the Hastings Valley (NSW). Berries with ripe rot tended to shrivel and acquired a distinctive off flavour and bitterness, described as hessian sack and musty. Wine made from the infected fruit had a higher pH and a higher level of residual sugar, but lower titratable acidity. Volatile acidity in wine made from uninfected fruit was 0.57 g/L, but increased to 0.83 and 1.06 g/L with 1.5 and 3% infection, respectively. Wine made from infected fruit had higher levels of both glycerol and gluconic acid indicative of fungal contamination. Alcohol concentration was also higher in wine made from infected fruit. Sensory analysis indicated that wine made from as low as 3% infected fruit had a similar colour density to control fruit, but a distinctive off-flavour, and browner colour hue. Conclusions: As far as we are aware of, this is the first report of a correlation between the level of grape infection by C. acutatum and wine composition in Australia. Significance of the Study: These results underline the problems of red grapes infected with C. acutatum. It provides viticulturists and winemakers with information to be considered when assessing grape quality and winemaking process for red wines.

Fully Automated Flow Injection Analyser for the Determination of Volatile Acidity in Wines

A fully automated method based on both Flow Injection (FI) and analytical pervaporation for the determination of the volatile acidity in wine is here presented. Both the different hardware units that constitute the analyser and data collection are controlled by a computer. The method is based on pervaporation of the volatile compounds present in wine into an indicator solution and monitoring the absorbance change, which is correlated with the volatile acidity content. The control software was developed with Java, C and XML programming languages. The analysis frequency and the precision of the method were 10 samples per hour and 0.035 g l − 1, respectively. The validation of the method was carried out with respect to the Mathieu method. The proposed method correlates (r = 0.95) with the Mathieu method (the standard method in wineries).

Effect of fermentation conditions and immobilization supports on the wine making

Batch and continuous fermentations at two different temperatures using immobilized cells on apple, quince and pear pieces were carried out separately and the effect of fermentation temperature, type of fermentation and immobilization support on kinetic parameters and on quality characteristics of the produced wines was investigated. Duncan’s multiple range test showed that higher temperature (30 °C) resulted in higher wine productivity. Statistically higher wine productivity was also observed when quince-immobilized biocatalyst was used in continuous fermentation compared to batch system at the same temperature. In contrast, wine productivity was statistically higher in batch fermentations compared to continuous process when apple and pear-supported biocatalysts were employed in wine making at 15 °C. Although volatile acidity in wines produced by immobilized cells on pear pieces was a little increased and statistically higher compared to wines produced by immobilized cells on apple and quince pieces, it still remained in levels usually found in dry wines. No vinegar odor was observed. Ethyl acetate concentration was higher in wines produced at lower temperature (15 °C) contributing to the fruity character of the product. The content of methanol, amyl and higher (propanol-1 and isobutanol) alcohols in all wines was found in very low levels, leading to improved quality products. Low-temperature (15 °C) wine-fermentation resulted in improved quality and the produced wines had a distinctive aromatic profile. Apple appears to have an advantage over quince and pear, as it is widely cultivated, it is considered more compatible with wine taste, while continuous process using immobilized cells on apple pieces resulted in high wine productivity.

Semiautomatic Flow-Injection Method for Determination of Volatile Acidity in Wines

A flow-injection (FI) method based on analytical pervaporation was assessed for its routine use in the determination of volatile acidity in winery laboratories. The new method was compared with both the official method and the Mathieu method, which is most often used in Spanish wineries, by testing 30 different wines, including young and aged, and sweet and dry wines from Montilla-Moriles appellation d'origine. The robustness of the new method was established, and then all 3 methods were studied in terms of range of linearity and regression of the calibration curve, repeatability, reproducibility, sensitivity, detection and quantitation limits (LOD and LOQ, respectively), and time of analysis. The FI method surpassed the Mathieu method in reproducibility and both the Mathieu and official methods in LOD and LOQ and sensitivity; it also required less personnel involvement and shorter analysis time. The statistical criteria established by the Office International de la Vigne et du Vin were applied to the data and the results obtained indicated that the differences between the analytical parameters of the 3 methods are not significant and can be applied indistinctly. The correlation of the methods was studied by taking them 2 by 2, and the corresponding equations, coefficients, and deviations confirmed the statistical results. Thus, the new method can be used in winery laboratories with clear advantages over its 2 counterparts (the routine and official methods).

Sequential determination of total and volatile acidity in wines based on a flow injection-pervaporation approach

A method for the sequential determination of the total and volatile acidity in wines based on the use of a pervaporator inserted in a continuous manifold is reported. The chemical principle is the colour change of bromothymol blue in the presence of the analytes and monitoring of the absorbance at 616 nm. The simultaneous injection of two sample aliquots into two channels allows one of the plugs to be driven to the pervaporator and the other directly to the photometric detector after merging with an indicator stream. After pervaporation, the acceptor stream, also containing the indicator, is led to the photometric detector for monitoring. The detection limits and relative standard deviation are 10 meq l −1, 1.0%, and 0.02 g l −1, 5.0%, for total and volatile acidity, respectively. The method has been applied to white and red wines from different origins and the results obtained are in good agreement with those of the standard method used in Spanish wine industries.

Total Volatile Acidity in Wines, Exclusive of Sulfur Dioxide: Collaborative Study

Abstract Two methods for determining total volatile acidity in wines, exclusive of sulfur dioxide, were collaboratively studied by using a matched pair scheme. Both methods required an alkali titration of a steam distillate of wine. With one method, the titration of the distillate gave total volatile acidity measurements exclusive of sulfur dioxide when mercuric ions were present during distillation (direct-titration method). With the other method, the interferences of free and bound sulfur dioxide were excluded following the alkali titration by titrating their equivalence as acetic acid with iodine (back-titration method). This required additional manipulation of the sample, including 2 extra titrations. The results of the collaborative study showed that although the mean measurements for both methods were close, variability in repeatability and reproducibility was always smaller (both among and within laboratories) for the directtitration method. This method has been adopted as official first action.

Effect of Lactic Acid on Volatile Acid Determination of Wine

The influence of lactic acid on the volatile acidity of wines was determined by three methods: a microdiffusion method; a steam-distillation method; and a new method developed from a modification of the steam-distillation technique. The new method employed the use of mercuric oxide to complex the sulfur dioxide in the wine samples. This modified method showed good correlation of results with those obtained by the standard steam-distillation procedure. All three methods resulted in low recoveries of lactic, acid from wines containing various levels of lactic acid. The diffusion method had less than 0.5% recovery and the two distillation methods about 2%. If was concluded that increases in volatile acidity of wines having undergone a malo-lactic fermentation is probably the result of the formation of acetic acid, the production of lactic acid contributing little increase.

Total Volatile Acidity in Wine

Total Volatile Acidity in Wine

Total Volatile Acidity in Wines

Abstract The determination of the total volatile acidity of wines has been studied collaboratively, using modern equipment now available. Procedures studied employed the Cash Electric Still and conventional apparatus, an all-glass unit. Results were good on both types of apparatus and between collaborators. It is recommended that the method, using either type of apparatus, be adopted as official, first action.